Metamagnetism and long range ordering in μ-1,3 bridging transition metal thiocyanato coordination polymers

First row transition metal(II) thiocyanate complexes, and formation of 1-, 2-, and 3-dimensional extended network structures of M(NCS)2(solvent)2 (M = Cr, Mn, Co) composition

The reaction of first row transition M(II) ions with KSCN in various solvents form tetrahedral (NMe4)2[M(II)(NCS)4] (M = Fe, Co), octahedral trans-M(II)(NCS)2(Sol)4 (M = Fe, V, Ni; Sol = MeCN, THF), and K4[M(II)(NCS)6] (M = V, Ni). The reaction of M(NCS)2(OCMe2)2 (M = Cr, Mn) in MeCN and [Co(NCMe)6](BF4)2 and KSCN in acetone and after diffusion of diethyl ether form M(NCS)2(Sol)2 that structurally differ as they form one-dimensional (1-D) (M = Co; Sol = THF), two-dimensional (2-D) (M = Mn; Sol = MeCN), and three-dimensional (3-D) (M = Cr; Sol = MeCN) extended structures. 1-D Co(NCS)2(THF)2 has trans-THFs, while the acetonitriles have a cis geometry for 2- and 3-D M(NCS)2(NCMe)2 (M = Cr, Mn). 2-D Mn(NCS)2(NCMe)2 is best described as Mn(II)(μ(N,N)-NCS)(μ(N,S)-NCS)(NCMe)2 [= Mn2(μ(N,N)-NCS)2(μ(N,S)-NCS)2(NCMe)4] with the latter μ(N,S)-NCS providing the 2-D connectivity. In addition, the reaction of Fe(NCS)2(OCMe2)2 and 7,7,8,8-tetracyanoquino-p-dimethane (TCNQ) forms 2-D structured Fe(II)(NCS)2TCNQ. The magnetic behavior of 1-D Co(NCS)2(THF)2 can be modeled by a 1-D Fisher expression (H = -2JS(i)·S(j)) with g = 2.4 and J/kB = 0.68 K (0.47 cm(-1)) and exhibit weak ferromagnetic coupling. Cr(NCS)2(NCMe)2 and Fe(II)(NCS)2TCNQ magnetically order as antiferromagnets with Tc's of 37 and 29 K, respectively, while Mn(NCS)2(NCMe)2 exhibits strong antiferromagnetic coupling. M(NCS)2(THF)4 and K4[M(NCS)6] (M = V, Ni) are paramagnets with weak coupling between the octahedral metal centers.

catena-Poly[[[bis-(methanol-κO)bis-(seleno-cyanato-κN)manganese(II)]-μ-1,2-bis-(pyridin-4-yl)eth-ene-κ(2) N:N'] 1,2-bis-(pyridin-4-yl)eth-ene mono-solvate]

In the crystal structure of the title compound, {[Mn(NCSe)2(C12H10N2)(CH3OH)2]·C12H10N2} n , the Mn(II) cation is coordin-ated by two terminal N-bonded seleno-cyanate anions, two methanol mol-ecules and two 1,2-bis-(pyridin-4-yl)eth-ene (bpe) ligands within a slightly distorted octahedral geometry. The Mn(II) cations are linked into chains along the c-axis direction by the bpe ligands, which are further connected by inter-molecular O-H⋯N hydrogen bonding between the methanol H atoms and additional bpe mol-ecules that are not coordinated to the metal atoms. The Mn(II) cation and both crystallographically independent bpe ligands are located on centers of inversion, whereas the seleno-cyanate and methanol ligands occupy general positions.

catena-Poly[[[bis(methanol-κO)bis(selenocyanato-κN)manganese(II)]-μ-1,2-bis(pyridin-4-yl)ethane-κ2N:N′] 1,2-bis(pyridin-4-yl)ethane monosolvate]

The reaction of manganese seleno­cyanate with 1,2-bis­(pyridin-4-yl)ethane (bpa) leads to the title compound, {[Mn(NCSe)₂(C₁₂H₁₂N₂)(CH₃OH)₂]·C₁₂H₁₂N₂}_n. The Mn^II cation is coordinated by two N-bonded seleno­cyanate anions, two bpa ligands and two O-bonded methanol mol­ecules, within a slightly distorted octa­hedral geometry. The Mn^II cations and the non-coordinating N-donor ligands are located on centers of inversion while the coordinating N-donor co-ligands are located on a twofold rotation axis. In the crystal, the Mn^II cations are linked into chains along the c-axis direction by the bpa ligands. The chains are further connected via a non-coordinating bpa ligand into layers parallel to (3-10) via O—H⋯N hydrogen-bonding inter­actions.

Tris[4-(dimethyl-amino)-pyridinium] hexa-kis-(thio-cyanato-κN)ferrate(III) monohydrate

In the title compound, (C₇H₁₁N₂)₃[Fe(NCS)₆]·H₂O, the Fe^III cation is coordinated by six terminal N-bonded thio­cyanate anions into a discrete threefold negatively charged complex. Charge balance is achieved by three protonated 4-(dimethyl­amino)­pyridine cations. The asymmetric unit consists of one Fe^III cation, six thio­cyanate anions, three 4-(dimethyl­amino)­pyridinium cations and one water mol­ecule, all of them located in general positions.

Bis[4-(dimethyl-amino)-pyridinium] bis-[4-(dimethyl-amino)-pyridine-κN (1)]tetra-kis-(thio-cyanato-κN)manganate(II)

In the crystal structure of the title compound, (C₇H₁₁N₂)₂[Mn(NCS)₄(C₇H₁₀N₂)₂], the manganese(II) cations are coordinated by four N-bonded thio­cyanate anions and two N-bonded 4-(dimethyl­amino)­pyridine ligands into discrete complex dianions. For charge balance, two 4-(dimethylamino)pyridine counter cations are present, which do not coordinate to the metal cation. The asymmetric unit consists of one manganese(II) cation, four thio­cyanate anions and two 4-(dimethyl­amino)­pyridine ligands, as well as two protonated 4-(dimethyl­amino)­pyridinium cations. The discrete complex anions are connected to the non-coordinating pyridinium cations by weak N—H⋯S hydrogen-bonding inter­actions.

Diaqua-bis-[2,6-bis-(4H-1,2,4-triazol-4-yl)pyridine-κN(2)]bis-(seleno-cyanato-κN)cobalt(II)

In the title compound, [Co(NCSe)₂(C₉H₇N₇)₂(H₂O)₂], the Co²⁺ cation is coordinated by two seleno­cyanate anions, two 2,6-bis­(4H-1,2,4-triazol-4-yl)pyridine ligands and two water mol­ecules within a slightly distorted N₄O₂ octa­hedron. The asymmetric unit consists of one Co²⁺ cation, which is located on a center of inversion, as well as one seleno­cyanate anion, one 2,6-bis­(4H-1,2,4-triazol-4-yl)pyridine ligand and one water mol­ecule in general positions. Inter­molecular O—H⋯N hydrogen bonds join the complex mol­ecules into layers parallel to the bc plane. The layers are linked by C—H⋯N and C—H⋯Se hydrogen bonds into a three-dimensional supra­molecular architecture.

Bis(3-acetyl-pyridine-κN)diaqua-bis-(seleno-cyanato-κN)cobalt(II)

In the crystal structure of the title compound, [Co(NCSe)(2)(C(7)H(7)NO)(2)(H(2)O)(2)], the Co(2+) cation is coordinated by two seleno-cyanate anions, two 3-acetyl-pyridine ligands and two water mol-ecules within a slightly distorted CoN(4)O(2) octa-hedron. The asymmetric unit consists of one Co(2+) cation, which is located on a center of inversion, as well as one seleno-cyanate anion, one 3-acetyl-pyridine ligand and one water mol-ecule in general positions. Whereas one of the water H atoms makes a classical O-H⋯O hydrogen bond, the other shows a O-H⋯Se inter-action.